Some studies in adults suggest that omega-3 fatty acids may be beneficial in the treatment of mild to moderate depression, but more research is needed.

Fish oil is a good source of omega-3 fatty acids, which play an important role in brain function. People with depression may have low blood levels of brain chemicals called eicosapentaenoic (i-koe-suh-pen-tuh-e-NO-ik) acid (EPA) and docosahexaenoic (doe-koe-suh-hek-suh-e-NO-ik) acid (DHA). EPA and DHA can be found in fish oil.

Eating fish a few times a week may provide your body with these healthy oils. Examples of fish high in omega-3s include sardines, salmon, herring, trout and canned white (albacore) tuna. Because some types of fish have higher levels of mercury than others, follow the recommendations of the Food and Drug Administration (fda.gov), especially if you're pregnant or nursing.

While it's generally true that the best way to get nutrients is through healthy foods, this is one example where a supplement may help. Some studies have shown that contaminants such as mercury do not appear to accumulate in fish oil, but remain primarily in the meat of the fish. So if you're concerned about mercury, a high-quality fish oil supplement may help with depression, but ask your doctor for advice.

Although using fish oil is generally safe, taking too much can increase your risk of bleeding and might suppress your immune response, so take fish oil supplements only under a doctor's supervision.

Fish oil isn't considered a replacement for treatment of depression, but it may be helpful as an addition to prescribed medications or other treatment. Although more studies are needed to determine exactly what role omega-3s play in depression, it's possible that fish oil supplements high in omega-3s may help lower the risk of depression — and omega-3 fatty acids help reduce high triglyceride levels and may help protect heart health.